摘要
胶东地区大规模金成矿作用发生于125~110Ma,具有西部早、东部晚的特点。本文选择了与金成矿作用同期的早白垩世晚期泽头花岗岩体为研究对象,开展了详细的岩相学、全岩主微量元素地球化学、锆石LA-ICP-MS U-Pb年代学及SrNd-Hf同位素研究,进行系统区域对比,探讨岩石成因和区域成矿构造动力学背景。泽头岩体锆石U-Pb年龄为115.6±1.1Ma(MSWD=1.7);属高钾-钙碱性系列,高Y(12.6×10-6~14.3×10-6)、低Sr/Y比值(36.5~44.8),具明显的稀土元素分馏(LREE/HREE=21.9~24.0,(La/Yb)N=33.4~39.1)和微弱的Eu异常(δEu=1.08~1.15)。P2O5含量0.07%~0.08%,与SiO2相关关系不明显,然A/CNK多小于1.1,显示Ⅰ型花岗岩石的特征。较晚侏罗世(165~150Ma)和早白垩世早期(140~125Ma)两期岩浆活动,泽头岩体所属的早白垩世晚期岩浆岩Y含量高,Sr/Y比值低,εNd(t)值、εHf(t)值高。与胶东地区金成矿年龄相似,早白垩世晚期岩体成岩年龄具有相同的空间变化规律,东部较西部约晚5Myr。早白垩世晚期岩体自西向东具明显的(87Sr/86Sr)j降低、εNd(t)升高特征,可能由胶东东部和西部基底物质组成差异引起。
The large-scale gold mineralization in the Jiaodong Peninsula occurred from 125 Ma to 110 Ma,with progressively younger ages from west to east.In this paper,Early Cretaceous Zetou pluton,emplaced coevally with the gold mineralization,is selected to reveal its petrogenesis using detailed lithography,whole rock major and trace elements geochemistry,zircon LA-ICP-MS U-Pb chronology and Sr-Vd-Hf isotopes geochemistry,shedding new lights on dynamic control on regional mineralization.Zetou pluton is characterized by high-K calc-alkaline feature,high Y content C12.6×10-6~14.3×10-6 D,low Sr/Y ratio C36.5~44.8 D,as well as significant rare earth element fractionation CLREE/HREE=21.9~24.0,CLa/YbDN=33.4~39.1 D and weak Eu anomaly GδEu=1.08~1.15 D.Zircon U-Pb age of the pluton is 115.6±1.1 Ma CMSWD=1.7 D.The contents of P2 O5 are 0.07%~0.08%,showing no obvious correlation with Si02.A/CNK are less than 1.1,which are consistent with the typical I-type granite trends.Compared with the Late Jurassic C165~150 MaD and the early stage of Early Cretaceous C140~125 MaD igneous rocks,plutons emplacing in 125~110 Ma,the late stage of Early Cretaceous in the Jiaodong region show higher Y content,lower Sr/Y ratio and higher whole-rock εNd CtD and zircon εHf CtD value.Similar to the regional variation of gold mineralization ages,the emplacement ages of the late stage of Early Cretaceous CAptian to AlbianD plutons in the eastern part of Jiaodong are about 5 Myr later than those in the western part.For this period of granitic magmatism,the eastern intrusions show lower C87Sr/86SrDi and higher εNd CtD than the western ones,which may be caused by differences of basement material composition between the eastern and western parts of the Jiaodong Peninsula.
作者
董学
李大鹏
赵睿
王欣然
王庆飞
DONG Xue;LI DaPeng;ZHAO Rui;WANG XinRan;WANG QingFei(Suate Key Laboratory of Geulogical Preses and Mineral Resurces,China Univrsiy of Gosiences,Beijing 0003,China;Ministry of Nabural Resources Key Laboralary of Gold Minealisution Prcesses and Resoures Unilisution,Key Labondlory of Metallogenie-Geolagie Poeceses and Comprehensine Uilisution of Minerals Resources in Shundong Pruince,Sharndong Insiute of Geolagical Sciences,Jinan 250013.China.;China Aer Gephysical Surnery and Remule Sensing Canler for Naturul Resources,Bejing 100083,China;Shaundong Geophysical and Gochenmical Explorution Imusilude,Jinan 250013,China)
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2020年第5期1501-1514,共14页
Acta Petrologica Sinica
基金
国家科技部111项目(BP0719021)
国家自然科学基金项目(41772076、41672084、41372086、41503038)联合资助.
关键词
泽头岩体
胶东金矿
早白垩世晚期
成岩成矿
东西差异
Zetou pluton
Jiaodong gold deposit
Late stage of Early Cretaceous
Petrogenesis and mineralization
Differences between the eastern and western parts
